Motor driven color screen



Dec. l5, 1936.

A. NEWMAN MOTOR DRIVEN COLOR SCREEN Filed Sept. 8, 1933 2 Sheets-Sheet 1 Dec. 15, 1936. v A. l. NEWMANA MOTOR DRIVEN coLoR SCREEN Filed Sept. 8, '1933 2 Sheets-Sheet 2 @kzal/@Pf I latented Dec. l5, 1936 tin Uhlii' S'ia PATENT @Fri MOTOR DRH/'EN COLOR SCREEN Alexander I. Newman, Chicago, Ill., assigner to Precision Scientirlc Company, Chicago, lll., a corporation of Iliinois Application September 8, 1933, Serial No. 688,547

1 Claim.

This invention relates to motor driven color screens of the type adapted for use in the motion picture industry, theatrical work and the like, for projecting beams of light of various colors upon a stage o1' screen or other display device. It is desirable in such operations to employ screens of a number of diiierent colors through which the beam of light may be caused to pass successively in order to produce varying color eiects upon i the stage, screen cr the like and it is frequently important to producers to produce changes in the color effects with uniform regularity. Heretofore, this regularity of operation has been difcult to attain with motors of the types commonly employed and the expense of operation has been much greater than should be necessary for actuating a rotating screen.

The principal object of the present invention is to overcome the foregoing difficulties by providing a new form of motor driven color screen in which a rotatable shaft, carrying a disk provided with panes or sections of varying colors, through which the light is to be projected, is driven by a motor of a synchronous type, such as that which has heretofore been used for driving the secondary clocks in an electric clock system. Such motors are disclosed, -for example, in the United States patents of Henry E. Warren, No. 1,283,432, dated October 29, 1918, and No. 1,456,082, dated May 22, 1923. It has been found that by employing electric motors of this synchronous type, preferably in conjunction with the power transmitting mechanism shown in the last-mentioned patent, it is possible to obtain new and improved results in the operation of a rotary color screen inasmuch as the power may be applied with a minimum cost and a uniform slow speed is capable of being maintained at all times so that the color screen may be maintained in continuous operation while at the same time producing changes of color on the stage or screen at intervals which are spaced apart suiiciently for all practical purposes. Other objects of the invention relate to various features of construction and arrangement which will appear more fully hereinatter.

The nature of the invention will be understood from thefollowing specification taken with the accompanying drawings in which one embodiment is illustrated.

in the drawings,-

Figure 1 shows a front elevation of the motor driven color screen embodying the improvements of the present invention;

Fig. 2 shows an enlarged axial section through (Cl. Mil-3.1)

the motor by which the shaft of the color screen is driven;

Fig. 3 shows an enlarged vertical section on the line 3-3 of Fig. 1; and

Fig. 4 shows a somewhat diagrammatic end elevation oi the motor shown in Fig. 2, the View being a section taken on the line li--4 of Fig. 3.

As illustrated in the drawings, the invention is embodied in a form of apparatus comprising a rotatable color screen It in the form of a disk comprising a hub IU, radial arms lb, and a circumferential rim Ic, forming intervening spaces which are occupied by panes or sheets II made of suitable translucent material, the several sheets being colored with different colors so that when the light beams are projected therethrough a plurality of diferent color ellects may be produced successively upon the stage or screen, or other display device. The hub portion lil is clamped between the complementary parts of a hub or cylinder I2 which is secured upon a shaft I3 by means of a set screw it. rThis shaft is adapted to be driven by the mechanism hereinafter described to effect the rotation of the screen Ill which is adapted to revolve in front of a metal disk I5, of circular form, attached to the front end of a tubular casing Il. The disk l5 has outturned ilanges l5a located adjacent the periphery of the disk iii and the disk i5 is secured to casing Il by means of bolts I8 so that an opening 15b formed in the disk I5 is located opposite to a lens i9 mounted in the casing and adapted to have light projected therethrough from an incandescent light bulb 20. Thus, as the color screen I revolves, the various colors represented by the different panes or sections I I of the screen are thrown successively upon the stage or screen.

The lens i9 is held in place within a metal ring 2| by means of a wire clamping ring 22 and this ring 2i, which is of cylindrical form, has outturned flanges which are secured to the casing Il. The light bulb 2li which is of the usual type eme pioyed in projection work, being one of suitable high power with a concentrated ilament, is

mounted in a socket 25 carried by a block 26 which is in turn positioned within a downward extension 2l of the casing Il. This casing is provided with a slot 27a in its lower wall to be engaged by a bolt 28 projecting downwardly through the socket 25 and the block 26, to be engaged at its lower end by a washer 29 and a wing nut 3@ by which the block 2E and the light bulb 2t may be clamped in adjusted position in order to locate the iilamerlt of the lamp at the desired point with respect to y'the focal point of the lens I9, thereby causing a beam of light, such as a concentrated beam or a flood-light beam, to be projected as desired. The casing 27 is attached to a supporting bracket 3I carried by a base plate 32 adapted to rest upon a table or other support. The bracket 3| has arms extending on opposite sides of the auxiliary casing 21 and a bolt 33 is attached to the walls of the casing and the arms of the bracket with a wing nut 34 engaging one end thereof so that the casing 21 and the main casing Il may be adjusted to assume the desired angle for projecting the light beam upon a stage, screen, or other display device. The casing II is closed at its rear end by a removable cap or cover 35 and in the upper part of the main casing, a series of Ventilating openings 36 are provided.

A pair of electrical conductors 3i, leading from a source of alternating current supply, are connected to the terminals of the socket 25 in which the bulb 20 is mounted, and branch conductors 38 lead from the terminals of the lamp socket to the terminals of a synchronous motor 40 which is mounted in a casing 4I secured to the rear side of the disk or plate I5.

The synchronous motor 40, shown particularly in Figs. 2 and 4, comprises a eld magnet 42, of laminated construction, which is mounted in a vertical position and which is carried by insulating posts 43, extending therefrom in a forward direction with their forward ends reduced in diameter and set into apertures formed in a plate 44. This plate and the posts 43 are attached to the plate or disk I5 by means of set screws 45. The rear ends of the posts 44 are reduced in diameter to engage apertures in the laminations of the field magnet and washers 46 are seated against the rear or inner ends of these posts and engaged by set screws 4'I which are threaded into the posts for holding the parts in assembled relation.

The field magnet 42 is energized by a coil 48'v connected in an alternating current circuit. The pole pieces 49 and 50 of the field magnet are split and one-half of each pole piece has mounted thereon a shading coil 5|. These shading coils are connected in the alternating current circuit and they cause the magnetism in the curved pole faces 52 and 53 to lag behind the magnetism in the other two pole faces 54 and 55. The ends of opposite pole pieces are spaced apart to leave air gaps 56 and the curved pole faces 52, 53, 54, and 55 are arranged to t against a tubular casing 5l, of cylindrical form, which is closed at one end and which is united at the other end with the end wall of a larger cylindrical casing 58, closed at its outer end. This casing 58 is located between the field magnet and the plate or disk I5 and is adapted to contain certain reducing gearing 59 by which the speed of the rotor shaft 6B is reduced and the power thereof transmitted to the previously described shaft I3 upon which the color screen I is mounted. The rotor 5| is mounted on the inner end of the shaft 68 between the pole faces of the eld magnet and Within the casing 5l which engages these pole faces. The rotor 6i comprises a disk 62 formed of hardened steel and secured upon the shaft ED. This disk carries two diametrically located pins 63 formed of magnetizable material, preferably hardened steel,

and these pins project from the face of the disk parallel to the aXis of the shaft 60 and between the opposite pole faces. With this arrangement, the rotating magnetic field set up by the alternating current passing through the magnetizing coils of the eld magnet, results in a magnetization of the rotor 6l and the resulting rotation thereof between the pole faces.

As set forth in the prior patents above referred to, a motor thus constructed, has a strong starting torque and has comparatively large power when brought up to synchronous speed. The strong starting characteristic is derived from the disk 62 and when the motor has been brought up to synchronous speed, the distribution of the magnetic flux is such that the projecting pins 63 become strongly polarized and are capable of driving the rotor against a much heavier resistance than could be overcome by the disk alone. The rotor thus comprises a non-polar disk provided with a plurality of projecting pins of magnetic material which extend into the magnetic eld in a region outside of that in which the disk rotates. Motors of this type are commonly known in the trade as telechron motors and have heretofore been employed in electric clock systems. It has been found, however, that the motors may be employed with great advantage in driving a rotary color screen such as that herein disclosed. The rotor operates with uni- F form speed 'depending only upon the frequency of the current supplied to the motor and by the use of the reducing gearing 59, located in the casing 58, it is possible to eifect such a reduction of speed between the shafts 60 and I3 that the latter` shaft may be made to rotate, for example, at a speed of one revolution per minute which is suitable for bringing about the desired periodic change of the color effect upon the stage or screen.

An important advantage of the present invention is that the apparatusshown in the drawings may be duplicated and a plurality of such units employed for projecting separate beams of light upon the same stage, or screen, or other display device, in which case all the motors operate simul' taneously at synchronous speeds and light beams of the same color are projected for equal synchronous periods of time by the lamps and colored screen sections of the several units.

Although one form of the invention has been shown or described by way of illustration, it will be understood that it may be constructed in various other embodiments coming within the scope of the appended claim.

I claim:

The combination with a plurality of color screens each having a plurality of translucent sections of different colors, of illuminating means for each screen, and a plurality of separate telechron motors connected in the same alternating current electrical system and each connected to rotate one of said screens, whereby said screens are rotated at synchronous speeds and said illuminating means are caused to project light beams through sections of the same color in different screens for equal synchronous periods of time.

ALEXANDER I. NEWMAN. 

